Preprints
Filtering by Subject: Geochemistry
Reproducibility in subsurface geoscience
Published: 2021-10-26
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Environmental Education, Environmental Health and Protection, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Mineral Physics, Natural Resource Economics, Natural Resources and Conservation, Natural Resources Management and Policy, Oil, Gas, and Energy, Other Earth Sciences, Other Environmental Sciences, Paleobiology, Paleontology, Sedimentology, Soil Science, Speleology, Stratigraphy, Sustainability, Tectonics and Structure, Volcanology, Water Resource Management
Reproducibility, the extent to which consistent results are obtained when an experiment or study is repeated, sits at the foundation of science. The aim of this process is to produce robust findings and knowledge, with reproducibility being the screening tool to benchmark how well we are implementing the scientific method. However, the re-examination of results from many disciplines has caused [...]
Constraints on the ice composition of carbonaceous chondrites from their magnetic mineralogy
Published: 2021-10-22
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Planetary Sciences
Carbonaceous chondrites experienced varying degrees of aqueous alteration on their parent asteroids, which influenced their mineralogies, textures, and bulk chemical and isotopic compositions. Although this alteration was a crucial event in the history of these meteorites, their various alteration pathways are not well understood. One phase that formed during this alteration was magnetite, and [...]
Improving the reliability of Fe- and S-XANES measurements in silicate glasses: Correcting beam damage and identifying Fe-oxide nanolites in hydrous and anhydrous melt inclusions
Published: 2021-10-19
Subjects: Geochemistry, Geology, Mineral Physics, Physical Sciences and Mathematics, Volcanology
The redox state of silicate melts influences crystallization, element partitioning, and degassing behavior. Synchrotron-based micro-X-ray absorption near edge structure (μXANES) spectroscopy has emerged as a powerful tool for determining redox conditions through the direct measurement of speciation of multivalent elements such as iron and sulfur in silicate glasses. In particular, the high [...]
Consistent Controls on Trace Metal Micronutrient Speciation in Wetland Soils and Stream Sediments
Published: 2021-10-15
Subjects: Biogeochemistry, Geochemistry, Soil Science
Trace metal are essential for microbially-mediated biogeochemical processes occurring in anoxic wetland soils and stream bed sediments, but low availability of these elements may inhibit anaerobic element cycling and transformations. Solid-phase speciation is likely a critical control on trace metal availability but has seen limited study in anoxic systems having concentrations similar to [...]
Boron isotope evidence for devolatilized and rehydrated recycled materials in the Icelandic mantle source
Published: 2021-09-30
Subjects: Geochemistry, Geology
Enriched mantle heterogeneities are widely considered to be generated through subduction, but the connections between specific subducted materials and the chemical signatures of mantle heterogeneities are not clearly defined. Boron is strongly isotopically fractionated at the surface and traces slab devolatilization, making it a potent tracer of previously subducted and recycled materials. Here, [...]
The hydrochemical signature of incongruent weathering in Iceland
Published: 2021-09-29
Subjects: Geochemistry
Basaltic watersheds such as those found in Iceland are thought to be important sites of CO₂ sequestration via silicate weathering. However, determining the magnitude of CO₂ uptake depends on accurately interpreting river chemistry. Here, we compile geochemical data from Iceland and use them to constrain weathering processes. Specifically, we use a newly developed inverse model to quantify solute [...]
Stalagmite evidence for Early Holocene multidecadal hydroclimate variability in Ethiopia
Published: 2021-09-22
Subjects: Geochemistry, Geology, Speleology
A multiproxy oxygen and carbon isotope (d13C and d18O), growth rate and trace element stalagmite paleoenvironmental record is presented for the Early Holocene from Achere Cave, Ethiopia. The annually laminated stalagmite grew from 10.6 to 10.4 ka, and from 9.7 to 9.0 ka with a short hiatus at ~9.25 ka. Using oxygen and carbon isotopic, and cave monitoring data, we demonstrate that the stalagmite [...]
The ‘europium anomaly’ in plants: facts and fiction
Published: 2021-09-08
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Life Sciences, Plant Sciences
Aims Rare earth elements (REEs) and normalized REE patterns determined in plant and soil samples represent powerful tools to trace biogeochemical processes during weathering, soil genesis and processes in the rhizosphere, and thus publications reporting rare earth elements and normalized REE patterns in soil systems and plants are rapidly increasing. Methods A normalized REE pattern allows [...]
Assessing pyrite-derived sulfate in the Mississippi River with four years of sulfur and triple-oxygen isotope data
Published: 2021-09-02
Subjects: Geochemistry
Riverine dissolved sulfate (SO42−) sulfur and oxygen isotope variations reflect their controls such as SO42− reduction and re-oxidation, and source mixing. However, unconstrained temporal variability of riverine SO42− isotope compositions due to short sampling durations may lead to mischaracterization of SO42− sources, particularly for the pyrite-derived sulfate load. We measured the sulfur and [...]
Centennial- and orbital-scale erosion beneath the Greenland Ice Sheet
Published: 2021-08-31
Subjects: Earth Sciences, Geochemistry, Geomorphology, Glaciology
Erosion beneath glaciers and ice sheets is a fundamental Earth-surface process dictating landscape development, which in turn influences ice-flow dynamics and the climate sensitivity of ice masses. The rate at which subglacial erosion takes place, however, is notoriously difficult to observe because it occurs beneath modern glaciers in a largely inaccessible environment. Here, we present 1) [...]
Oxidized Mantle Sources of HIMU and EM-type Ocean Island Basalts
Published: 2021-08-31
Subjects: Earth Sciences, Geochemistry, Geology
Oxygen fugacity (fO2) is a fundamental variable in igneous petrology with utility as a potential tracer of recycled surficial materials in the sources of mantle-derived lavas. It has been postulated that ocean island basalts (OIB) have elevated fO2 relative to mid-ocean ridge basalts (MORB) owing to more oxidized source regions. To clarify this issue, trace-element systematics of olivine grains [...]
Safety and Belonging in the Field: A Checklist for Educators
Published: 2021-08-19
Subjects: Atmospheric Sciences, Biogeochemistry, Climate, Cosmochemistry, Earth Sciences, Education, Environmental Education, Environmental Health and Protection, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Environmental Studies, Fresh Water Studies, Geochemistry, Geographic Information Sciences, Geography, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Higher Education, Human Geography, Hydrology, Life Sciences, Meteorology, Mineral Physics, Natural Resource Economics, Natural Resources and Conservation, Natural Resources Management and Policy, Nature and Society Relations, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Oil, Gas, and Energy, Other Earth Sciences, Other Environmental Sciences, Other Geography, Other Oceanography and Atmospheric Sciences and Meteorology, Other Planetary Sciences, Outdoor Education, Paleobiology, Paleontology, Physical and Environmental Geography, Physical Sciences and Mathematics, Planetary Biogeochemistry, Planetary Geochemistry, Planetary Geology, Planetary Geomorphology, Planetary Geophysics and Seismology, Planetary Glaciology, Planetary Hydrology, Planetary Mineral Physics, Planetary Sciences, Planetary Sedimentology, Remote Sensing, Sedimentology, Social and Behavioral Sciences, Soil Science, Spatial Science, Speleology, Stratigraphy, Sustainability, Tectonics and Structure, Volcanology, Water Resource Management
Ensuring taught fieldwork is a positive, generative, collective, and valuable experience for all participants requires considerations beyond course content. To guarantee safety and belonging, participants’ identities (backgrounds and protected characteristics) must be considered as a part of fieldwork planning and implementation. Furthermore, getting fieldwork right is an important step in [...]
Dissolution precipitation creep as a process for the strain localisation in mafic rocks
Published: 2021-08-17
Subjects: Earth Sciences, Geochemistry, Tectonics and Structure
Unaltered mafic rocks consist of mechanically strong minerals (e.g. pyroxene, plagioclase and garnet) that can be deformed by crystal plastic mechanisms only at high temperatures (>800°C). Yet, many mafic rocks do show extensive deformation by non-brittle mechanisms when they have been subjected to lower temperature conditions. In such cases, the deformation typically is assisted by mineral [...]
A strontium isoscape of Italy for provenance studies
Published: 2021-08-06
Subjects: Geochemistry
We present a novel database of environmental and geological 87Sr/86Sr values (n = 1920) from Italy, using literature data and newly analysed samples, for provenance purposes. We collected both bioavailable and non-bioavailable (i.e. rocks and bulk soils) data to attain a broader view of the Sr isotope variability of the Italian peninsula. These data were used to build isotope variability maps, [...]
Impact of Zn Substitution on Fe(II)-induced Ferrihydrite Transformation Pathways
Published: 2021-07-29
Subjects: Geochemistry
Iron oxide minerals are ubiquitous in soils, sediments, and aquatic systems and influence the fate and availability of trace metals. Ferrihydrite is a common iron oxide of nanoparticulate size and poor crystallinity, serving as a thermodynamically unstable precursor to more crystalline phases. While aging induces such phase transformations, these are accelerated by the presence of dissolved [...]